Before you begin

Install IBM Load Balancer and assign two static IP addresses to it. The server selected for the Load Balancer installation must reside on the same LAN segment as the nodes to be clustered.

About this task

Configure IBM Load balancer to support your cluster using MAC Address rewriting. With this method, the load balancer receives a packet intended for the cluster. It uses configured metrics to determine which node in the cluster should process the message, and then sends the message back out to the network, routing it to the appropriate node's MAC address.

Each of the nodes in the cluster is configured with a loopback adapter; when the packet is rewritten to the network, the appropriate node will receive and process the packet.

Procedure

Configure the nodes of the cluster.

For cluster nodes running on Windows

Add a loopback adapter with the IP address of the cluster on each of the nodes of the cluster. For instructions, see the Load Balancer for IPv4 and IPv6 administration guide.

For cluster nodes running on IBM i

Use the Add TCP/IP Interface command to create a virtual IP address with the "cluster" IP address you want to use.

For example:

ADDTCPIFC INTNETADR('192.0.2.0') LIND(*VIRTUALIP) SUBNETMASK(*HOST)

When the virtual TCP/IP interface is started, the server accepts packets for that address.

Note: Do not enable proxy ARP for the Virtual IP Address. In other words, do not specify the PREFIFC parameter on the command or enable proxy through the graphical user interface configuration. Doing so prevents multiple systems from using the same "cluster" IP address simultaneously.

Configure port settings on the cluster nodes so that IBM Load Balancer can route the packets properly:

IBM Load Balancer requires every node in the cluster to use same port number for both HTTP and HTTPS service (typically, port 80). If you have configured your nodes to use unique port numbers, change them to the same port now.

Tip: When configuring the ports, you can use the wildcard * when specifying the host name for the HTTP and HTTPS. This will listen on all interfaces configured in the system, including the loopback adapter set up for the cluster.

On the load balancer server, configure load balancing for the cluster:

If you are using IPv6 addresses, enable the processing of IPv6 packets:

Run the following command while logged in as the Windows administrator:

netsh interface ipv6 install

Theis command enables processing of IPv6 packets. Issue this command only once; thereafter, you can start and stop the executor as often as you need. If you do not issue the command to enable processing of IPv6 packets on these systems, the executor will not start.

Start the executor function of the dispatcher:

dscontrol executor start

Add the cluster to the service:

dscontrol cluster add cluster's_fully_qualified_host_name

where cluster's_fully_qualified_host_name is the fully qualified host name that you assigned to the cluster when you installed the load balancer; for example:

stms-cluster.example.com

.

Add the cluster port:

dscontrol port add cluster's_fully_qualified_host_name@port

where cluster's_fully_qualified_host_name@port is the fully qualified host name that you assigned to the cluster when you installed the load balancer, with the HTTP/HTTPS port appended to it (typically port 80); for example:

stms-cluster.example.com@80

Add the nodes for which this server will balance workload:

dscontrol server add cluster_host@port@primary_node

dscontrol server add cluster_host@port@secondary_node

where:

cluster_host@port@primary_node indicates the cluster's fully qualified host name with the port appended (as in the previous step) plus now with the primary node's fully qualified host name appended; for example:

stms-cluster.example.com@80@meetsvr1.example.com

cluster_host@port@secondary_node indicates the cluster's fully qualified host name with the port appended (as in the previous step) plus now with the secondary node's fully qualified host name appended (include an additional line for each additional secondary node); for example:

stms-cluster.example.com@80@meetsvr2.example.com

Add the cluster to the executor:

dscontrol executor add cluster's_fully_qualified_host_name

where cluster's_fully_qualified_host_name is the fully qualified host name that you assigned to the cluster when you installed the load balancer; for example:

stms-cluster.example.com

.

Start the manager:

dscontrol manager start

Start the HTTP advisor for the port you are using (the port you specified in the previous steps, typically port 80):

dscontrol advisor start http 80

Now you can stop the service:

dsserver stop

Close the command window.

Define server affinity with a "sticky time":

By default the Load Balancer will round-robin HTTP requests between the cluster members, so that a single client may be routed to different cluster members for subsequent requests rather than continuing to be routed to the same cluster member. Since a client typically accesses an online meeting every 30-40 seconds during the session, you may want to enable server affinity for a Sametime® cluster so that the client continues to access the same server during a single meeting.

The dispatcher component of IBM Load Balancer supports a configurable "sticky time". This means that the load balancer will remember which cluster member a client was routed to; subsequent requests will "stick to" the same server until the preset time expires. IBM recommends a "sticky" time configuration of 60 seconds for a Sametime cluster.

Windows

Start IBM Load Balancer.

In the navigation tree, select the Executor (the load balancer's non-forwarding IP address, which appears under its host name).